This invention relates to an optical connection device for use in optically connecting a plurality of optical nodes to one another and to an optical coupler used in the optical connection device.
In order to process a great deal of information, development is progressive or advanced in regard to a computer which is capable of executing calculation at a very high speed. In this event, it is known in the art that sequential processing which uses electric circuitry is about to approach a performance limit in processing speed. Taking this into consideration, a parallel processing architecture has been researched in a super computer or an array processor to concurrently execute calculations.
in the meanwhile, it is to be noted that a light beam is excellent for parallel processing because the light beam is spacially expanded and has a physical property in which no interference takes place one another. Accordingly, a recent interest is directed to parallel processing which uses the light beam or beams, rather than parallel processing using electric signals.
In order to accomplish such parallel processing by the use of the light beams, the light beams are inevitably optically coupled to or combined with one another. For this purpose, the light beams are often deflected by an optical deflector from the others. Such an optical deflector is formed by a hologram technique or a prism. However, it is difficult to precisely design or manufacture the optical deflector. Moreover, the optical deflector needs an intricate optical system to optically couple the optical deflector to another device or circuit.
In order to solve such a disadvantage, a proposal is made about a planar optical connection device by H. J. Haumann et al in Conference Record of '90 International Topical Meeting on Optical Computing under the title of "Optical Bus Based on Light-guided-plates". With this planar optical connection device, an optical beam or a light beam is distributed by a hologram. However, the planar optical connection device is disadvantageous in that only a small amount of light is utilized in the optical connection device and unnecessary diffraction light beams objectionably occur.
Alternatively, an optical beam distributor is disclosed in Japanese Unexamined Patent Publication Tokko Hei 2-34814, namely, 34814/1990, to optically and concurrently distribute a light beam emitted from a light source, to a plurality of light reception elements or optical receivers, such as phototransistors, which are electrically coupled to an integrated circuit formed on a planar substrate. Specifically, the optical beam distributor comprises a semi-spherical surface to which a plurality of lenses are located so that each lens can receive the light beam. The optical beam is distributed through the lenses as output light beams onto the light reception elements formed on the planar substrate. With this structure, it is possible to supply each of the light reception elements with the output light beams without deviation of optical axes and without aberration. Therefore, the optical beam distributor is effective to concurrently feed clock pulses from the light source to the respective light reception elements.
Thus, the optical beam distributor is available for transmitting a single light source to a plurality of light reception elements. However, consideration is made neither about transmitting a light beam through the planar substrate nor about bidirectional communication among optical terminals or nodes, such as light sources and reception elements.